JP2014161944A - Profile adjustment method of polishing member used in polishing device, and polishing device - Google Patents

Abstract

A polishing member profile adjusting method capable of realizing a target polishing member profile is provided.
In this method, the surface height of the polishing member is measured in each of a plurality of swing sections Z1 to Z5 preset on the polishing member along the swinging direction of the dresser. The difference between the current profile obtained from the measured value and the target profile of the polishing member 10 is calculated, and the moving speed of the dresser 5 in the plurality of swing sections Z1 to Z5 is corrected so as to eliminate the difference. .
[Selection] Figure 5

Description

The present invention relates to a method for adjusting a profile of a polishing member used in a polishing apparatus for polishing a substrate such as a wafer.
The present invention also relates to a polishing apparatus for polishing a substrate.

  In recent years, with the progress of high integration of semiconductor devices, circuit wiring has been miniaturized, and the dimensions of the integrated devices are being further miniaturized. Therefore, it is necessary to polish a wafer having a film of metal or the like formed on its surface to flatten the surface of the wafer. As one of the planarization methods, there is polishing by a chemical mechanical polishing (CMP) apparatus. The chemical mechanical polishing apparatus has a polishing member (a polishing cloth, a polishing pad, etc.) and a holding part (a top ring, a polishing head, a chuck, etc.) for holding an object to be polished such as a wafer. Then, the surface of the polishing object (surface to be polished) is pressed against the surface of the polishing member, and while supplying a polishing liquid (abrasive liquid, chemical liquid, slurry, pure water, etc.) between the polishing member and the polishing object, By relatively moving the polishing member and the polishing object, the surface of the polishing object is polished flat. According to the polishing by the chemical mechanical polishing apparatus, good polishing is performed by the chemical polishing action and the mechanical polishing action.

  As a material of the polishing member used in such a chemical mechanical polishing apparatus, a foamed resin or a nonwoven fabric is generally used. Fine irregularities are formed on the surface of the polishing member, and the minute irregularities act as chip pockets effective for preventing clogging and reducing polishing resistance. However, if polishing of the object to be polished is continued with the polishing member, fine irregularities on the surface of the polishing member are crushed, causing a reduction in the polishing rate. For this reason, dressing (sharpening) of the surface of the polishing member is performed with a dresser in which a large number of abrasive grains such as diamond particles are electrodeposited, and fine irregularities are re-formed on the surface of the polishing member.

  As a dressing method of the polishing member, a method using a dresser (large diameter dresser) equal to or larger than a region used for polishing the polishing member, or a dresser (smaller than a region used for polishing the polishing member) There is a method using a small diameter dresser). When using a large-diameter dresser, for example, the dressing surface on which the abrasive grains are electrodeposited is pressed against the rotating polishing member while performing dressing while rotating the dresser while fixing the position of the dresser. When using a small-sized dresser, for example, the dressing surface is pressed against the rotating polishing member while dressing the rotating dresser while moving (reciprocating or swinging in a circular or linear shape). When dressing while rotating the polishing member in this way, the region actually used for polishing of the entire surface of the polishing member is an annular region centering on the rotation center of the polishing member.

  At the time of dressing the polishing member, the surface of the polishing member is scraped off even though the amount is small. Therefore, if dressing is not performed appropriately, the surface of the polishing member will be improperly undulated and there will be a disadvantage that the polishing rate will vary within the surface to be polished. Variations in the polishing rate cause poor polishing, and it is necessary to perform dressing that does not cause inappropriate undulations on the surface of the polishing member. That is, dispersion of the polishing rate is achieved by performing dressing under appropriate dressing conditions such as an appropriate rotation speed of the polishing member, an appropriate rotation speed of the dresser, an appropriate dressing load, and an appropriate moving speed of the dresser in the case of a small-diameter dresser. It is avoiding.

JP 2010-76049 A

Patent Document 1 discloses that the surface of the polishing member is made uniform by swinging the dresser at a preset speed for each swinging section of the dresser. However, the conventional dressing method sometimes fails to obtain the intended profile of the polishing member.
The present invention has been made to solve the above-described conventional problems, and an object thereof is to provide a polishing member profile adjustment method capable of realizing a target polishing member profile.
Another object of the present invention is to provide a polishing apparatus capable of executing such a method for adjusting the profile of the polishing member.

  In order to achieve the above-described object, one aspect of the present invention is a method for adjusting a profile of a polishing member used in a polishing apparatus for a substrate, wherein the polishing member is swung on the polishing member. Dressing and measuring the surface height of the polishing member in each of a plurality of swing sections preset on the polishing member along the swinging direction of the dresser, and obtaining from the measured value of the surface height The difference between the obtained current profile and the target profile of the polishing member is calculated, and the movement speed of the dresser in the plurality of swing sections is corrected so that the difference is eliminated.

In a preferred aspect of the present invention, the step of calculating a difference between the current profile and the target profile calculates a cut rate of the polishing member for the plurality of swing sections from the measured value of the surface height, It is a step of calculating a difference between the calculated cut rate and a preset target cut rate for each of the plurality of swing sections.
In a preferred aspect of the present invention, the step of correcting the movement speed of the dresser includes the step of correcting the dresser on the polishing member in the plurality of swing sections according to the difference between the calculated cut rate and the target cut rate. This is a step of correcting the moving speed.
In a preferred aspect of the present invention, the step of calculating the difference between the calculated cut rate and the target cut rate is a step of calculating a cut rate ratio that is a ratio of the calculated cut rate to the target cut rate. And the step of correcting the moving speed of the dresser is a step of multiplying the moving speed of the dresser on the polishing member in the plurality of swing sections by the cut rate ratio, respectively.

In a preferred aspect of the present invention, the dressing time of the polishing member after correcting the moving speed of the dresser is calculated, the dressing time of the polishing member before correcting the moving speed of the dresser, and the dressing after the correction. The method further includes the step of multiplying the corrected moving speed by an adjustment coefficient for eliminating time and difference.
In a preferred aspect of the present invention, the adjustment coefficient is a ratio of the dressing time after correction to the dressing time before correction.

A preferred embodiment of the present invention measures the film thickness of the substrate polished by the polishing member, and based on the difference between the remaining film thickness profile obtained from the measurement value of the film thickness and the target film thickness profile, The corrected moving speed is further corrected.
In a preferred aspect of the present invention, the step of further correcting the corrected moving speed calculates a polishing rate of the substrate in a plurality of regions arranged in a radial direction of the substrate from the measured value of the film thickness, A target polishing rate set in advance for each of the regions is calculated, a cut rate of the polishing member in the swing section corresponding to the plurality of regions is calculated, the polishing rate, the target polishing rate, and the cut rate The correction coefficient is calculated from the above, and the correction coefficient is multiplied by the corrected moving speed in the swing section.
In a preferred aspect of the present invention, an initial film thickness profile and a target film thickness profile of the substrate are acquired, a target polishing amount distribution is calculated from a difference between the initial film thickness profile and the target film thickness profile, and the target The corrected moving speed is further corrected based on the distribution of the polishing amount.

  Another aspect of the present invention is a polishing apparatus for polishing a substrate, the polishing table supporting a polishing member, a top ring that presses the substrate against the polishing member, and swinging on the polishing member. A dresser for dressing the member; a dressing monitoring device for adjusting a profile of the polishing member; and a plurality of swing sections preset on the polishing member along a swinging direction of the dresser. A surface height measuring device for measuring the surface height, the dressing monitoring device calculates a difference between a current profile obtained from the measurement value of the surface height and a target profile of the polishing member; The moving speed of the dresser in the plurality of swing sections is corrected so that the difference is eliminated.

In a preferred aspect of the present invention, the step of calculating a difference between the current profile and the target profile executed by the dressing monitoring apparatus is configured to calculate a cut rate of the polishing member from the measured surface height. It is a step of calculating a swing section and calculating a difference between the calculated cut rate and a preset target cut rate for each of the plurality of swing sections.
In a preferred aspect of the present invention, the step of correcting the moving speed of the dresser executed by the dressing monitoring device is performed according to the difference between the calculated cut rate and the target cut rate. It is a step of correcting the moving speed of the dresser on the polishing member.
In a preferred aspect of the present invention, the step of calculating the difference between the calculated cut rate and the target cut rate executed by the dressing monitoring device is a ratio of the calculated cut rate to the target cut rate. A step of calculating a cut rate ratio, and the step of correcting the moving speed of the dresser executed by the dressing monitoring device includes the cutting speed to the moving speed of the dresser on the polishing member in the plurality of swinging sections. It is a step of multiplying each rate ratio.

In a preferred aspect of the present invention, the dressing monitoring device calculates the dressing time of the polishing member after correcting the moving speed of the dresser, and the dressing time of the polishing member before correcting the moving speed of the dresser. The method further includes the step of multiplying the corrected moving speed by an adjustment coefficient for eliminating the difference from the corrected dressing time.
In a preferred aspect of the present invention, the adjustment coefficient is a ratio of the dressing time after correction to the dressing time before correction.

In a preferred aspect of the present invention, the polishing apparatus further includes a film thickness measuring device that measures the film thickness of the substrate polished by the polishing member, and the dressing monitoring apparatus is obtained from the measured value of the film thickness. Further, the corrected moving speed is further corrected based on the difference between the remaining film thickness profile and the target film thickness profile.
In a preferred aspect of the present invention, the step of further correcting the corrected moving speed executed by the dressing monitoring device includes the step of measuring the substrate in a plurality of regions arranged in the radial direction of the substrate from the measured value of the film thickness. A polishing rate is calculated, a target polishing rate set in advance for the plurality of regions is prepared, a cut rate of the polishing member in the swing section corresponding to the plurality of regions is calculated, the polishing rate, A correction coefficient is calculated from a target polishing rate and the cut rate, and the correction coefficient is multiplied by the corrected moving speed in the swing section.
In a preferred aspect of the present invention, the dressing monitoring apparatus acquires an initial film thickness profile and a target film thickness profile of the substrate, and a distribution of a target polishing amount from a difference between the initial film thickness profile and the target film thickness profile. And the corrected moving speed is further corrected based on the distribution of the target polishing amount.

  In accordance with the present invention, a current profile of the abrasive member is generated from a measurement of the surface height of the abrasive member dressed by the dresser, and based on the difference between the target profile and the current profile, the dresser on the abrasive member. The movement speed is corrected. By swinging the dresser at the movement speed corrected in this way, the target profile can be realized with high accuracy.

It is a schematic diagram which shows the grinding | polishing apparatus which grind | polishes substrates, such as a wafer. It is a top view which shows a dresser and a polishing pad typically. FIG. 3A to FIG. 3C are diagrams showing examples of dressing surfaces. It is a figure which shows the rocking | swiveling area defined on the polishing surface of a polishing pad. It is a figure which shows the dresser movement speed distribution before correction | amendment, and the dresser movement speed distribution after correction | amendment. It is a figure which shows the grinding | polishing apparatus provided with the film thickness measuring machine provided away from the grinding | polishing table. It is a figure which shows the substrate processing apparatus provided with the grinding | polishing apparatus and the film thickness measuring machine.

  An embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a schematic view showing a polishing apparatus for polishing a substrate such as a wafer. As shown in FIG. 1, the polishing apparatus includes a polishing table 9 that holds a polishing pad (polishing member) 10, a polishing unit 1 for polishing a wafer W, and a polishing liquid that supplies a polishing liquid onto the polishing pad 10. A supply nozzle 4 and a dressing unit 2 for conditioning (dressing) the polishing pad 10 used for polishing the wafer W are provided. The polishing unit 1 and the dressing unit 2 are installed on the base 3.

  The polishing unit 1 includes a top ring (substrate holding part) 20 connected to the lower end of the top ring shaft 18. The top ring 20 is configured to hold the wafer W on the lower surface thereof by vacuum suction. The top ring shaft 18 is rotated by driving a motor (not shown), and the top ring 20 and the wafer W are rotated by the rotation of the top ring shaft 18. The top ring shaft 18 moves up and down with respect to the polishing pad 10 by a vertical movement mechanism (not shown) (for example, a servo motor and a ball screw).

  The polishing table 9 is connected to a motor 13 disposed below the polishing table 9. The polishing table 9 is rotated around its axis by a motor 13. A polishing pad 10 is affixed to the upper surface of the polishing table 9, and the upper surface of the polishing pad 10 constitutes a polishing surface 10 a for polishing the wafer W.

  The polishing of the wafer W is performed as follows. The top ring 20 and the polishing table 9 are rotated to supply the polishing liquid onto the polishing pad 10. In this state, the top ring 20 holding the wafer W is lowered, and the wafer W is pressed against the polishing surface 10 a of the polishing pad 10 by a pressurizing mechanism (not shown) including an airbag installed in the top ring 20. . The wafer W and the polishing pad 10 are brought into sliding contact with each other in the presence of the polishing liquid, whereby the surface of the wafer W is polished and flattened.

  The dressing unit 2 includes a dresser 5 that contacts the polishing surface 10 a of the polishing pad 10, a dresser shaft 16 connected to the dresser 5, an air cylinder 19 provided at the upper end of the dresser shaft 16, and the dresser shaft 16. And a dresser arm 17 to be supported. Abrasive grains such as diamond particles are fixed to the lower surface of the dresser 5. The lower surface of the dresser 5 constitutes a dressing surface for dressing the polishing pad 10.

  The dresser shaft 16 and the dresser 5 can move up and down with respect to the dresser arm 17. The air cylinder 19 is a device that applies a dressing load to the polishing pad 10 to the dresser 5. The dressing load can be adjusted by the air pressure supplied to the air cylinder 19.

  The dresser arm 17 is driven by a motor 56 and is configured to swing around a support shaft 58. The dresser shaft 16 is rotated by a motor (not shown) installed in the dresser arm 17, and the dresser 5 rotates about its axis by the rotation of the dresser shaft 16. The air cylinder 19 presses the dresser 5 against the polishing surface 10 a of the polishing pad 10 with a predetermined load via the dresser shaft 16.

  Conditioning of the polishing surface 10a of the polishing pad 10 is performed as follows. The polishing table 9 and the polishing pad 10 are rotated by a motor 13, and a dressing liquid (for example, pure water) is supplied to the polishing surface 10 a of the polishing pad 10 from a dressing liquid supply nozzle (not shown). Further, the dresser 5 is rotated around its axis. The dresser 5 is pressed against the polishing surface 10a by the air cylinder 19, and the lower surface (dressing surface) of the dresser 5 is brought into sliding contact with the polishing surface 10a. In this state, the dresser arm 17 is turned to swing the dresser 5 on the polishing pad 10 in the substantially radial direction of the polishing pad 10. The polishing pad 10 is scraped off by the rotating dresser 5 so that the polishing surface 10a is conditioned.

  A pad height sensor (surface height measuring machine) 40 for measuring the height of the polishing surface 10 a is fixed to the dresser arm 17. A sensor target 41 is fixed to the dresser shaft 16 so as to face the pad height sensor 40. The sensor target 41 moves up and down integrally with the dresser shaft 16 and the dresser 5, while the vertical position of the pad height sensor 40 is fixed. The pad height sensor 40 is a displacement sensor, and the height of the polishing surface 10a (the thickness of the polishing pad 10) can be indirectly measured by measuring the displacement of the sensor target 41. Since the sensor target 41 is coupled to the dresser 5, the pad height sensor 40 can measure the height of the polishing surface 10 a during the conditioning of the polishing pad 10.

  The pad height sensor 40 indirectly measures the polishing surface 10a from the vertical position of the dresser 5 in contact with the polishing surface 10a. Accordingly, the average height of the polishing surface 10 a with which the lower surface (dressing surface) of the dresser 5 is in contact is measured by the pad height sensor 40. As the pad height sensor 40, any type of sensor such as a linear scale sensor, a laser sensor, an ultrasonic sensor, or an eddy current sensor can be used.

  The pad height sensor 40 is connected to the dressing monitoring device 60, and the output signal of the pad height sensor 40 (that is, the measured value of the height of the polishing surface 10a) is sent to the dressing monitoring device 60. Yes. The dressing monitoring device 60 acquires the profile of the polishing pad 10 (cross-sectional shape of the polishing surface 10a) from the measured value of the height of the polishing surface 10a, and further determines whether the conditioning of the polishing pad 10 is performed correctly. It has a function to do.

  The polishing apparatus includes a table rotary encoder 31 that measures the rotation angle of the polishing table 9 and the polishing pad 10, and a dresser rotary encoder 32 that measures the turning angle of the dresser 5. The table rotary encoder 31 and the dresser rotary encoder 32 are absolute encoders that measure the absolute value of the angle. These rotary encoders 31 and 32 are connected to a dressing monitoring device 60. The dressing monitoring device 60 is configured to measure the rotation angle of the polishing table 9 and the polishing pad 10 when the height of the polishing surface 10a is measured by the pad height sensor 40. Furthermore, the turning angle of the dresser 5 can be acquired.

  The dresser 5 is connected to a dresser shaft 16 via a universal joint 15. The dresser shaft 16 is connected to a motor (not shown). The dresser shaft 16 is rotatably supported by a dresser arm 17. The dresser arm 17 causes the dresser 5 to swing in the radial direction of the polishing pad 10 as shown in FIG. 2 while contacting the polishing pad 10. It has become. The universal joint 15 is configured to transmit the rotation of the dresser shaft 16 to the dresser 5 while allowing the dresser 5 to tilt. The dressing unit 2 is configured by the dresser 5, the universal joint 15, the dresser shaft 16, the dresser arm 17, and a rotation mechanism (not shown). The dressing unit 2 is electrically connected to a dressing monitoring device 60 that obtains the sliding distance of the dresser 5 by simulation. As the dressing monitoring device 60, a dedicated or general-purpose computer can be used.

  Abrasive grains such as diamond particles are fixed to the lower surface of the dresser 5. The portion to which the abrasive grains are fixed constitutes a dressing surface for dressing the polishing surface of the polishing pad 10. FIG. 3A to FIG. 3C are diagrams showing examples of dressing surfaces. In the example shown in FIG. 3A, abrasive grains are fixed to the entire lower surface of the dresser 5, and a circular dressing surface is formed. In the example shown in FIG. 3B, the abrasive grains are fixed to the peripheral portion of the lower surface of the dresser 5, and a ring-shaped dressing surface is formed. In the example shown in FIG. 3C, abrasive grains are fixed to the surface of a plurality of small diameter pellets arranged at substantially equal intervals around the center of the dresser 5, and a plurality of circular dressing surfaces are formed.

  When dressing the polishing pad 10, as shown in FIG. 1, the polishing pad 10 is rotated at a predetermined rotational speed in the direction of the arrow, and the dresser 5 is rotated at the predetermined rotational speed in the direction of the arrow by a rotation mechanism (not shown). Let In this state, the dressing surface of the dresser 5 (the surface on which the abrasive grains are arranged) is pressed against the polishing pad 10 with a predetermined dressing load to dress the polishing pad 10. Further, the dresser 5 swings on the polishing pad 10 by the dresser arm 17 to dress a region used for polishing the polishing pad 10 (polishing region, that is, a region for polishing an object to be polished such as a wafer). Can do.

  Since the dresser 5 is connected to the dresser shaft 16 via the universal joint 15, even if the dresser shaft 16 is slightly inclined with respect to the surface of the polishing pad 10, the dressing surface of the dresser 5 is appropriately applied to the polishing pad 10. Touch. A pad roughness measuring device 35 for measuring the surface roughness of the polishing pad 10 is disposed above the polishing pad 10. As the pad roughness measuring device 35, a known non-contact type surface roughness measuring device such as an optical type can be used. The pad roughness measuring device 35 is connected to the dressing monitoring device 60, and the measured value of the surface roughness of the polishing pad 10 is sent to the dressing monitoring device 60.

  A film thickness sensor (film thickness measuring machine) 50 that measures the film thickness of the wafer W is disposed in the polishing table 9. The film thickness sensor 50 is disposed facing the surface of the wafer W held on the top ring 20. The film thickness sensor 50 is a film thickness measuring machine that measures the film thickness of the wafer W while moving across the surface of the wafer W as the polishing table 9 rotates. As the film thickness sensor 50, a non-contact type sensor such as an eddy current sensor or an optical sensor can be used. The measured value of the film thickness is sent to the dressing monitoring device 60. The dressing monitoring device 60 is configured to generate a film thickness profile of the wafer W (film thickness distribution along the radial direction of the wafer W) from the film thickness measurement value.

  Next, the swing of the dresser 5 will be described with reference to FIG. The dresser arm 17 turns around the point J clockwise and counterclockwise by a predetermined angle. The position of this point J corresponds to the center position of the support shaft 58 shown in FIG. Then, as the dresser arm 17 turns, the center of rotation of the dresser 5 swings in the radial direction of the polishing pad 10 within the range indicated by the arc L.

  FIG. 4 is an enlarged view of the polishing surface 10 a of the polishing pad 10. As shown in FIG. 4, the swing range (swing width L) of the dresser 5 is divided into a plurality (five in FIG. 4) swing sections Z1, Z2, Z3, Z4, and Z5. These swinging sections Z1 to Z5 are virtual sections set in advance on the polishing surface 10a, and are aligned along the swinging direction of the dresser 5 (that is, the radial direction of the polishing pad 10). The dresser 5 dresses the polishing pad 10 while moving across these swinging sections Z1 to Z5. The lengths of the swing sections Z1 to Z5 may be the same as or different from each other.

  The moving speed of the dresser 5 when oscillating on the polishing pad 10 is set in advance for each of the oscillating sections Z1 to Z5. The dresser 5 crosses each of the swing sections Z1 to Z5 at a preset moving speed. The movement speed distribution of the dresser 5 represents the movement speed of the dresser 5 in each of the swing sections Z1 to Z5.

  The moving speed of the dresser 5 is one of the determinants of the cut rate profile of the polishing pad 10. The cut rate of the polishing pad 10 represents the amount (thickness) of the polishing pad 10 scraped off by the dresser 5 per unit time. Usually, since the thickness of the polishing pad 10 scraped in each of the swing sections Z1 to Z5 is different, the numerical value of the cut rate is also different for each swing section. However, since the pad profile is generally preferably flat, it may be adjusted so that the difference in the cut rate for each swing section is small. Here, increasing the moving speed of the dresser 5 means shortening the staying time of the dresser 5 on the polishing pad 10, that is, reducing the cut rate of the polishing pad 10. Decreasing means increasing the staying time of the dresser 5 on the polishing pad 10, that is, increasing the cut rate of the polishing pad 10. Therefore, by increasing the moving speed of the dresser 5 in a certain swinging section, the cut rate in that swinging section can be lowered, and by reducing the moving speed of the dresser 5 in a certain swinging section, the swinging speed thereof can be reduced. The cut rate in the moving section can be increased. With the above method, the cut rate profile of the entire polishing pad can be adjusted. The cut rate used in this method is a value obtained by dividing the amount of the polishing pad 10 scraped off in a certain swing section by “the dressing time of the entire polishing pad”, and “the stay time in each swing section”. It is not a divided value.

  The dressing monitoring device 60 stores a target profile of the polishing pad 10 (hereinafter referred to as a target pad profile). The target pad profile represents the target height distribution of the polishing surface 10 a along the radial direction of the polishing pad 10. This target pad profile is input to the dressing monitoring device 60 via an input device (not shown) and stored in a memory (not shown) inside the target pad profile. The dressing monitoring device 60 generates the current profile of the polishing pad 10 (hereinafter referred to as the current pad profile) from the measured value of the height of the polishing surface 10a, and calculates the difference between the current pad profile and the target pad profile. Then, based on this difference, the moving speed of the dresser 5 in the swing sections Z1 to Z5 is corrected.

  The difference between the current pad profile and the target pad profile is calculated for each of the swing sections Z1 to Z5. Therefore, the moving speed of the dresser 5 is corrected according to the difference calculated for each of the swing sections Z1 to Z5. More specifically, the moving speed of the dresser 5 is corrected so that the difference is eliminated. For example, the movement speed of the dresser 5 is reduced in the swing section where the measured pad height is higher than the target pad height at that time (target polishing surface height), and the measured pad height becomes the target value at that time. In the swinging section lower than the pad height, the moving speed of the dresser 5 is increased. The target pad height in each swing section is obtained from the target pad profile. Thus, the moving speed of the dresser 5 is corrected based on the difference between the current pad profile and the target pad profile.

  A more specific example of correcting the moving speed of the dresser 5 will be described below. In the following example, the ratio of the current cut rate to the target cut rate is calculated as the difference between the current pad profile and the target pad profile. The dressing monitoring device 60 calculates the cut rate of the polishing pad 10 for each of the plurality of swing zones Z1 to Z5 from the measured surface height, and the ratio of the calculated cut rate to the target cut rate (hereinafter, cut rate ratio). Is calculated for each of the plurality of rocking sections Z1 to Z5, and the obtained cut rate ratio is multiplied by the current moving speed of the dresser 5 in the plurality of rocking sections Z1 to Z5, respectively. The movement speed of the dresser 5 when swinging on the pad 10 is corrected.

  For example, when the target cut rate in the swing zone Z1 is 100 [μm / h] and the calculated current cut rate is 90 [μm / h], the cut rate ratio in the swing zone Z1 is 0.9 (= 90/100). Therefore, the dressing monitoring device 60 corrects the moving speed of the dresser 5 in the swinging section Z1 by multiplying the current moving speed in the swinging section Z1 by 0.9. When the current moving speed is multiplied by 0.9, the moving speed (swinging speed) of the dresser 5 is lowered. As a result, the staying time of the dresser 5 in the swing zone Z1 becomes longer, and the cut rate increases. In this way, the moving speed of the dresser 5 is corrected. Similarly, the movement speed of the dresser 5 is corrected in the other swing sections Z2 to Z5, and the movement speed distribution of the dresser 5 within the swing range L is adjusted accordingly.

  The target cut rate is set in advance for each of the swing zones Z1 to Z5. For example, if a flat polishing surface 10a is to be formed, the target cut rate may be the average of the measured cut rate over the entire polishing surface 10a, or the dressing monitoring device 60 in advance from an input device (not shown). It may be entered.

  FIG. 5 is a diagram showing a dresser movement speed distribution before correction and a dresser movement speed distribution after correction. In FIG. 5, the left vertical axis represents the cut rate of the polishing pad 10, the right vertical axis represents the moving speed of the dresser 5, and the horizontal axis represents the radial distance of the polishing pad 10. The solid line graph represents the dresser movement speed before correction, and the dotted line graph represents the dresser movement speed after correction.

  When the moving speed of the dresser 5 is corrected as shown in FIG. 5, the entire dressing time can change. Such a change in dressing time may affect other processes such as a wafer polishing process and a transfer process. Therefore, the dressing monitoring device 60 multiplies the corrected moving speed in the swing zone Z1 to Z5 by the adjustment coefficient so that the dressing time after correction of the moving speed of the dresser 5 becomes equal to the dressing time before correction. . For example, when the dressing time before correction is 10 seconds and the dressing time after correction is 13 seconds, the dressing monitoring apparatus 60 eliminates the difference of 3 seconds (that is, the dressing time after correction is 10 seconds). Adjustment coefficient is calculated, and this adjustment coefficient is multiplied by the corrected moving speed in each of the swing sections Z1 to Z5.

  The adjustment coefficient is a ratio of dressing time after correction to dressing time before correction (hereinafter referred to as dressing time ratio). In the above example, the dressing time before correction is 10 seconds and the dressing time after correction is 13 seconds, so the dressing time ratio is 1.3. Therefore, the dressing time ratio 1.3 is multiplied by the corrected moving speed in the swing zone Z1 to Z5. By adjusting the dressing time using such an adjustment coefficient, the dressing time can be kept constant regardless of the correction of the moving speed of the dresser 5.

  The dressing of the polishing pad 10 affects the polishing rate (also called removal rate) of the wafer. More specifically, the wafer polishing rate is high in a pad area where dressing is performed well, and the wafer polishing rate is low in a pad area where dressing is insufficient. Depending on the type of abrasive used, the opposite tendency may occur. In any case, there is a correlation between the cut rate of the polishing pad 10 and the polishing rate of the wafer. Therefore, the polishing rate of the wafer can be adjusted by adjusting the cut rate of the polishing pad 10.

  The dressing monitoring device 60 may further correct the moving speed of the dresser 5 based on the difference between the film thickness profile of the polished wafer and the target film thickness profile. Hereinafter, a specific example will be described. As shown in FIG. 1, the polishing apparatus includes a film thickness sensor 50. The dressing monitoring device 60 is connected to the film thickness sensor 50, generates a film thickness profile of the polished wafer (that is, a remaining film thickness profile) from the film thickness measurement value, and polishes the wafer at each position in the wafer radial direction. The rate is calculated.

  The dressing monitoring device 60 stores target polishing rates for a plurality of regions arranged in the wafer radial direction. The plurality of regions are regions defined in advance on the surface of the wafer, for example, a central region, an intermediate region, and an outer peripheral region of the wafer. The target polishing rate is input in advance to the dressing monitoring device 60 via an input device (not shown). The dressing monitoring device 60 may change the target polishing rate while confirming the actual polishing rate.

The dressing monitoring device 60 includes a polishing rate R calculated in a plurality of regions arranged in the radial direction of the wafer, a target polishing rate R_tar set in advance in the plurality of regions, and a swing section corresponding to the plurality of regions. From cut rate C
Correction coefficient = 1 / (1-K * (R-R_tar) / C)
And the movement speed is further corrected by multiplying the correction coefficient by the movement speed of the dresser 5 in the swing section. The correction coefficient is calculated for each of the swing sections Z1 to Z5 using the above formula. Here, K is a coefficient representing the relationship between the cut rate and the polishing rate, and is obtained in advance by experiments. K may be a constant or a function of the polishing rate R.

  The correction coefficient in the central area of the wafer is multiplied by the moving speed of the dresser 5 in the swing zone Z3 corresponding to the central area of the wafer, and the correction coefficient in the intermediate area of the wafer is the fluctuation coefficient corresponding to the intermediate area of the wafer. The moving speed of the dresser 5 in the moving sections Z2 and Z4 is multiplied, and the correction coefficient in the outer peripheral area of the wafer is multiplied by the moving speed of the dresser 5 in the swing sections Z1 and Z5 corresponding to the outer peripheral area of the wafer. . The swing sections corresponding to the center area, the intermediate area, and the outer peripheral area of the wafer are selected in advance from the swing sections Z1 to Z5. In this way, the polishing rate of the wafer can be controlled by adjusting the cut rate of the polishing pad 10 through the moving speed of the dresser 5.

  Since the remaining film thickness profile is acquired after the wafer is polished, the correction of the movement speed of the dresser 5 based on the remaining film thickness profile is reflected in the polishing of the next wafer. The dresser 5 dresses the polishing pad 10 under dressing conditions including the corrected moving speed, so that the pad profile approaches the target pad profile. Subsequent wafers are polished by the polishing pad 10 approaching the target pad profile.

  The dressing monitoring device 60 may correct the moving speed of the dresser 5 based on the difference between the initial film thickness profile of the wafer and the target film thickness profile. The dressing monitoring device 60 stores a target film thickness profile. This target film thickness profile is input in advance to the dressing monitoring device 60 via an input device (not shown). The dressing monitoring device 60 calculates the distribution of the target polishing amount from the difference between the initial film thickness profile and the target film thickness profile. The target polishing amount is a difference between the initial film thickness and the target film thickness for each wafer region, and is obtained by subtracting the target film thickness from the initial film thickness.

  The dressing monitoring device 60 corrects the corrected moving speed of the dresser 5 based on the distribution of the target polishing amount. Specifically, the movement speed of the dresser 5 is decreased in the swing section corresponding to the wafer region having a large target polishing amount, and the movement speed of the dresser 5 is decreased in the swing section corresponding to the wafer region having a small target polishing amount. increase. In this way, by adjusting the cut rate of the polishing pad 10 through the moving speed of the dresser 5, the polishing amount distribution of the wafer can be controlled.

  The initial film thickness measurement is performed by a film thickness measuring machine different from the film thickness sensor 50 before the wafer is polished. FIG. 6 is a view showing a polishing apparatus provided with a film thickness measuring device 55 provided apart from the polishing table 9. As the film thickness measuring device 55, a non-contact type film thickness measuring device such as an eddy current sensor or an optical sensor can be used. The wafer is first carried into the film thickness measuring device 55, where the initial film thickness is measured at a plurality of positions along the radial direction of the wafer. The measured value of the initial film thickness is sent to the dressing monitoring device 60, and an initial film thickness profile is generated from the measured value of the initial film thickness. As described above, the dressing monitoring device 60 corrects the corrected moving speed of the dresser 5 based on the distribution of the target polishing amount.

  The dresser 5 dresses the polishing pad 10 under dressing conditions including the corrected moving speed, so that the pad profile approaches the target pad profile. The wafer is transferred from the film thickness measuring device 55 to the top ring 20 by a transfer mechanism (not shown). The wafer is polished on the polishing pad 10 so that the polishing profile approaches the target polishing profile. The film thickness of the polished wafer may be measured by the film thickness sensor 50, or may be measured by the film thickness measuring device 55. The film thickness measuring device for measuring the initial film thickness may be provided inside the polishing apparatus or may be provided outside the polishing apparatus. For example, measurement information by a film thickness measuring device provided in a processing apparatus (for example, a film forming apparatus) in the previous stage of the polishing process may be sent to the dressing monitoring apparatus 60.

  Next, a detailed configuration of the substrate processing apparatus including the film thickness measuring device 55 and the polishing apparatus shown in FIG. 1 will be described with reference to FIG. The substrate processing apparatus is an apparatus that can perform a series of steps of polishing, cleaning, and drying a wafer. As shown in FIG. 7, the substrate processing apparatus includes a substantially rectangular housing 61, and the inside of the housing 61 is divided into a load / unload unit 70, a polishing unit 80, and a cleaning unit 90 by partition walls 61a and 61b. Has been. The substrate processing apparatus has an operation control unit 100 that controls a wafer processing operation. The dressing monitoring device 60 is built in the operation control unit 100.

  The load / unload unit 70 includes a front load unit 71 on which a wafer cassette for stocking a large number of wafers (substrates) is placed. A traveling mechanism 72 is laid along the front load unit 71 in the load / unload unit 70, and a transfer robot (loader) 73 that can move along the arrangement direction of the wafer cassette on the traveling mechanism 72. Is installed. The transfer robot 73 can access the wafer cassette mounted on the front load unit 71 by moving on the traveling mechanism 72.

  The polishing unit 80 is a region where a wafer is polished, and includes a first polishing apparatus 80A, a second polishing apparatus 80B, a third polishing apparatus 80C, and a fourth polishing apparatus 80D. The first polishing apparatus 80A includes a first polishing table 9A to which a polishing pad 10 having a polishing surface is attached, and a first polishing for holding the wafer and polishing the wafer while pressing the wafer against the polishing pad 10 on the polishing table 9A. A top ring 20A, a first polishing liquid supply nozzle 4A for supplying a polishing liquid (for example, slurry) or a dressing liquid (for example, pure water) to the polishing pad 10, and a dressing for the polishing surface of the polishing pad 10 A first dressing unit 2A, and a first atomizer 8A that sprays a mixed fluid of liquid (for example, pure water) and gas (for example, nitrogen gas) or a liquid (for example, pure water) in the form of a mist onto the polishing surface are provided.

  Similarly, the second polishing apparatus 80B includes a second polishing table 9B to which the polishing pad 10 is attached, a second top ring 20B, a second polishing liquid supply nozzle 4B, a second dressing unit 2B, and a second atomizer. The third polishing apparatus 80C includes a third polishing table 9C to which the polishing pad 10 is attached, a third top ring 20C, a third polishing liquid supply nozzle 4C, and a third dressing unit 2C. The fourth polishing apparatus 80D includes a fourth polishing table 9D to which the polishing pad 10 is attached, a fourth top ring 20D, a fourth polishing liquid supply nozzle 4D, and a fourth polishing liquid supply nozzle 4D. A dressing unit 2D and a fourth atomizer 8D are provided.

  The first polishing apparatus 80A, the second polishing apparatus 80B, the third polishing apparatus 80C, and the fourth polishing apparatus 80D have the same configuration, and have the same configuration as the polishing apparatus shown in FIG. That is, the top rings 20A to 20D, the dressing units 2A to 2D, the polishing tables 9A to 9D, and the polishing liquid supply nozzles 4A to 4D illustrated in FIG. 7 respectively include the top ring 20, the dressing unit 2, and the polishing table 9 illustrated in FIG. This corresponds to the polishing liquid supply nozzle 4. In FIG. 1, the atomizer is omitted.

  As shown in FIG. 7, a first linear transporter 81 is disposed adjacent to the first polishing apparatus 80A and the second polishing apparatus 80B. The first linear transporter 81 is a mechanism for transferring a wafer between four transfer positions (a first transfer position TP1, a second transfer position TP2, a third transfer position TP3, and a fourth transfer position TP4). Further, a second linear transporter 82 is disposed adjacent to the third polishing apparatus 80C and the fourth polishing apparatus 80D. The second linear transporter 82 is a mechanism for transporting a wafer between three transport positions (fifth transport position TP5, sixth transport position TP6, and seventh transport position TP7).

  A lifter 84 for receiving a wafer from the transfer robot 73 is disposed adjacent to the first transfer position TP1. The wafer is transferred from the transfer robot 73 to the first linear transporter 81 through the lifter 84. A shutter (not shown) is provided in the partition wall 61a between the lifter 84 and the transfer robot 73, and when transferring the wafer, the shutter is opened so that the wafer is transferred from the transfer robot 73 to the lifter 84. It has become.

  The film thickness measuring device 55 is disposed adjacent to the load / unload unit 70. The wafer is taken out from the wafer cassette by the transfer robot 73 and is carried into the film thickness measuring device 55. In the film thickness measuring device 55, the initial film thickness is measured at a plurality of positions along the radial direction of the wafer. After the initial film thickness is measured, the wafer is transferred to the lifter 84 by the transfer robot 73, further transferred from the lifter 84 to the first linear transporter 81, and transferred to the polishing apparatuses 80 </ b> A and 80 </ b> B by the first linear transporter 81. The The top ring 20A of the first polishing apparatus 80A moves between the upper position of the polishing table 9A and the second transport position TP2 by the swing operation. Therefore, the wafer is transferred to the top ring 20A at the second transfer position TP2.

  Similarly, the top ring 20B of the second polishing apparatus 80B moves between the upper position of the polishing table 9B and the third transfer position TP3, and the transfer of the wafer to the top ring 20B is performed at the third transfer position TP3. The top ring 20C of the third polishing apparatus 80C moves between the upper position of the polishing table 9C and the sixth transfer position TP6, and the transfer of the wafer to the top ring 20C is performed at the sixth transfer position TP6. The top ring 20D of the fourth polishing apparatus 80D moves between the upper position of the polishing table 9D and the seventh transfer position TP7, and the transfer of the wafer to the top ring 20D is performed at the seventh transfer position TP7.

  A swing transporter 85 is disposed between the first linear transporter 81, the second linear transporter 82, and the cleaning unit 90. Wafer transfer from the first linear transporter 81 to the second linear transporter 82 is performed by a swing transporter 85. The wafer is transferred to the third polishing apparatus 80C and / or the fourth polishing apparatus 80D by the second linear transporter 82.

  On the side of the swing transporter 85, a temporary placement table 86 for a wafer installed on a frame (not shown) is disposed. As shown in FIG. 7, the temporary placement table 86 is disposed adjacent to the first linear transporter 81 and is positioned between the first linear transporter 81 and the cleaning unit 90. The swing transporter 85 transports the wafer between the fourth transport position TP4, the fifth transport position TP5, and the temporary placement table 86.

  The wafer placed on the temporary placement table 86 is transferred to the cleaning unit 90 by the first transfer robot 91 of the cleaning unit 90. As shown in FIG. 7, the cleaning unit 90 includes a primary cleaning module 92 and a secondary cleaning module 93 that clean the polished wafer with a cleaning liquid, and a drying module 95 that dries the cleaned wafer. The first transfer robot 91 operates to transfer the wafer from the temporary placement table 86 to the primary cleaning module 92 and further transfer from the primary cleaning module 92 to the secondary cleaning module 93. A second transfer robot 96 is disposed between the secondary cleaning module 93 and the drying module 95. The second transfer robot 96 operates to transfer the wafer from the secondary cleaning module 93 to the drying module 95.

  The dried wafer is taken out from the drying module 95 by the transfer robot 73 and carried into the film pressure measuring device 55. The film thickness measuring device 55 measures the film thickness after polishing at a plurality of positions along the radial direction of the wafer. Usually, the measurement is performed at the same position as the initial film thickness measurement.

  The wafer for which measurement has been completed is taken out from the film thickness measuring device 55 by the transfer robot 73 and returned to the wafer cassette. In this way, a series of processes including polishing, cleaning, and drying are performed on the wafer.

  In the above description, the case where the dresser oscillates about the dresser swivel axis J as shown in FIG. 2 has been described. However, even when the dresser reciprocates linearly or performs any other motion, The invention can be applied. Furthermore, in the above description, the case where the cut rate is adjusted by adjusting the movement speed of the dresser has been described. However, the present invention is also applied to the case where the cut rate is adjusted by correcting the load or rotation speed of the dresser. Can do. In the above description, the case where the polishing member (polishing pad) rotates as shown in FIG. 1 has been described. However, the present invention can be applied even when the polishing member moves like an endless track.

DESCRIPTION OF SYMBOLS 1 Polishing unit 2 Dressing unit 3 Base 4 Polishing liquid supply nozzle 5 Dresser 8 Atomizer 9 Polishing table 10 Polishing pad 13 Motor 15 Universal joint 16 Dresser shaft 17 Dresser arm 18 Top ring shaft 19 Air cylinder 20 Top ring 31 Table rotary encoder 32 Dresser Rotary encoder 35 Pad roughness measuring instrument 40 Pad height sensor 41 Sensor target 50 Film thickness sensor 55 Film thickness measuring machine 56 Motor 58 Support shaft 60 Dressing monitoring device 61 Housing 70 Load / unload section 71 Front load section 72 Travel mechanism 73 Conveying robot 80 Polishing units 80A to 80D Polishing device 81 First linear transporter 82 Second linear transporter 84 Lifter 86 Temporary table 90 Cleaning unit 91 Tsu DOO 92 primary cleaning module 93 secondary cleaning modules 95 drying module 96 second transfer robot

Claims (18)

A method for adjusting a profile of a polishing member used in a substrate polishing apparatus,
Dressing the polishing member by swinging a dresser on the polishing member;
Measuring the surface height of the polishing member in each of a plurality of preset swing sections on the polishing member along the swinging direction of the dresser;
Calculating the difference between the current profile obtained from the measured surface height and the target profile of the abrasive member;
A method of correcting a moving speed of the dresser in the plurality of swing sections so that the difference is eliminated. Calculating the difference between the current profile and the target profile comprises:
Calculate the cut rate of the polishing member for the plurality of swing sections from the measured value of the surface height,
The method according to claim 1, further comprising calculating a difference between the calculated cut rate and a preset target cut rate for each of the plurality of swing sections.   The step of correcting the movement speed of the dresser is a step of correcting the movement speed of the dresser on the polishing member in the plurality of swing sections according to the difference between the calculated cut rate and the target cut rate. The method of claim 2, wherein: The step of calculating the difference between the calculated cut rate and the target cut rate is a step of calculating a cut rate ratio that is a ratio of the calculated cut rate to the target cut rate,
The step of correcting the moving speed of the dresser is a step of multiplying the moving speed of the dresser on the polishing member in the plurality of swing sections by the cut rate ratio, respectively. The method described. Calculate the dressing time of the polishing member after correcting the movement speed of the dresser,
The method further includes the step of multiplying the corrected moving speed by an adjustment factor for eliminating a difference between the dressing time of the polishing member before correcting the moving speed of the dresser and the dressing time after correction. The method according to any one of claims 1 to 4.   6. The method of claim 5, wherein the adjustment factor is a ratio of the dressing time after correction to the dressing time before correction. Measure the thickness of the substrate polished by the polishing member,
7. The corrected moving speed is further corrected based on a difference between a remaining film thickness profile obtained from the measured value of the film thickness and a target film thickness profile. The method according to one item. The step of further correcting the corrected moving speed includes:
Calculate the polishing rate of the substrate in a plurality of regions aligned in the radial direction of the substrate from the measured value of the film thickness,
Preparing a preset target polishing rate for the plurality of regions,
Calculating a cut rate of the polishing member in the swing section corresponding to the plurality of regions;
Calculating a correction coefficient from the polishing rate, the target polishing rate, and the cut rate;
The method according to claim 7, wherein the correction coefficient is a step of multiplying the corrected moving speed in the swing section by the correction coefficient. Obtain an initial film thickness profile and a target film thickness profile of the substrate,
From the difference between the initial film thickness profile and the target film thickness profile, calculate the distribution of the target polishing amount,
The method according to claim 7, wherein the corrected moving speed is further corrected based on the distribution of the target polishing amount. A polishing apparatus for polishing a substrate,
A polishing table for supporting the polishing member;
A top ring that presses the substrate against the polishing member;
A dresser for dressing the polishing member by swinging on the polishing member;
A dressing monitoring device for adjusting the profile of the polishing member;
A surface height measuring device that measures the surface height of the polishing member in each of a plurality of swing sections preset on the polishing member along the swinging direction of the dresser;
The dressing monitoring device comprises:
Calculating the difference between the current profile obtained from the measured surface height and the target profile of the abrasive member;
A polishing apparatus, wherein the moving speed of the dresser in the plurality of swing sections is corrected so that the difference is eliminated. Calculating the difference between the current profile and the target profile performed by the dressing monitoring device;
Calculate the cut rate of the polishing member for the plurality of swing sections from the measured value of the surface height,
The polishing apparatus according to claim 10, wherein the polishing apparatus is a step of calculating a difference between the calculated cut rate and a target cut rate preset for each of the plurality of swing sections.   The step of correcting the moving speed of the dresser executed by the dressing monitoring device includes the dresser on the polishing member in the plurality of swing sections according to the difference between the calculated cut rate and the target cut rate. The polishing apparatus according to claim 11, wherein the polishing apparatus is a step of correcting the moving speed of the polishing machine. The step of calculating the difference between the calculated cut rate and the target cut rate executed by the dressing monitoring device is a step of calculating a cut rate ratio that is a ratio of the calculated cut rate to the target cut rate And
The step of correcting the moving speed of the dresser executed by the dressing monitoring device is a step of multiplying the moving speed of the dresser on the polishing member in the plurality of swing sections by the cut rate ratio, respectively. The polishing apparatus according to claim 11. The dressing monitoring device comprises:
Calculate the dressing time of the polishing member after correcting the movement speed of the dresser,
The step of multiplying the corrected moving speed by an adjustment coefficient for eliminating a difference between the dressing time of the polishing member before correcting the moving speed of the dresser and the dressing time after correction is further performed. The polishing apparatus according to any one of claims 10 to 13.   The polishing apparatus according to claim 14, wherein the adjustment coefficient is a ratio of the dressing time after correction to the dressing time before correction. The polishing apparatus further comprises a film thickness measuring machine that measures the film thickness of the substrate polished by the polishing member,
The dressing monitoring device further corrects the corrected moving speed based on a difference between a remaining film thickness profile obtained from the measured value of the film thickness and a target film thickness profile. The polishing apparatus according to any one of 10 to 15. Further correcting the corrected travel speed performed by the dressing monitoring device,
Calculate the polishing rate of the substrate in a plurality of regions aligned in the radial direction of the substrate from the measured value of the film thickness,
Preparing a preset target polishing rate for the plurality of regions,
Calculating a cut rate of the polishing member in the swing section corresponding to the plurality of regions;
Calculating a correction coefficient from the polishing rate, the target polishing rate, and the cut rate;
The polishing apparatus according to claim 16, wherein the polishing apparatus is a step of multiplying the corrected moving speed in the swing section by the correction coefficient. The dressing monitoring device comprises:
Obtain an initial film thickness profile and a target film thickness profile of the substrate,
From the difference between the initial film thickness profile and the target film thickness profile, calculate the distribution of the target polishing amount,
The polishing apparatus according to claim 16, wherein the corrected moving speed is further corrected based on the distribution of the target polishing amount.

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